1. Field of the Invention
The field of this invention lies within the food pan and container art particularly as it relates to maintaining food at a desired temperature to limit spoilage, and enhance tastiness. More particularly, it lies within the art of maintaining food in a safe and improved temperature environment in a food pan or container. The food pan is surrounded by a medium such as a eutectic gel which can be a highly absorbent polymer. The eutectic gel is exposed to a relative temperature in order to bring the temperature of the eutectic gel to a desired level. Thus, when the food is placed within the pan having the eutectic gel exposed to a previous temperature, it helps to sustain the temperature of the food at a desirable level.
Such temperature controlled containers and pans utilizing eutectic gels are often used in commercial food service establishments. The food pans and containers with the eutectic gels can be utilized within the field of institutional food service such as restaurants, fast food restaurants, hospitals, schools, banquet facilities, and other related commercial and institutional food service activities. The end result is to provide for a desirable food service as to quality, temperature control, tastiness as well as attractive appearances of the food.
2. Prior Art
The prior art with respect to temperature controlled containers includes which have substances such as ice in various forms including dry ice and ice made from water. Utilization of such containers often times is cumbersome and difficult and, of course, requires large volumes of ice.
Of late, it has been established that containers having a eutectic gel surrounding them or in association therewith such as those items known as ice and heat packs that can be pre-chilled or frozen, can provide substantially superior maintenance of foods in a container. Also, such eutectic gels packs can be used for maintaining heat as well as cooling purposes.
When using eutectic gels, they should not be exposed to the food, which they are designed to maintain in a temperature-enhanced environment. As a consequence, any leakage of material from a package containing the eutectic gel or a container containing the eutectic gel into the food can be a drawback. In order to eliminate such exposure of food to the eutectic gel, it has been common to provide for an inner and outer shell with a eutectic gel there between.
The inner shell is utilized to hold the food and is in contact with the food. The outer shell surrounds the inner shell. In between the inner and outer shell, the eutectic gel is placed so that it can be cooled to a particular extent or maintained in any other suitable temperature or heat controlled environment.
In the past, the utilization of a lip or flange to interface between the inner and outer shells effectuated a sealing contact surface to maintain the eutectic gel between the inner and outer shells. This was effected by various means including adhesives that bonded the two respective inner and outer shells together.
The utilization of an adhesive or gluing agent was found to be difficult in application and sometimes did not provide for a sufficiently strong and complete seal. This, of course, led to the disassociation of the inner and outer shell and in some cases, a leakage of the eutectic gel into the inner position of the container containing the food.
This invention particularly enhances the securement of the inner and outer shell by means of an ultrasonic welding process. To this extent, the ultrasonic welding process utilizes an inner and outer shell which are bonded at a weld surface with an inner and outer respective flange, lip or ledge being secured together.
The inner and outer flanges, lips or ledges respectively have welding flanges, ribs, bands, strips, ridges, rims or protuberances, which can be indexed into welding grooves or channels. The welding channels or grooves receive the protuberances or ridges in an indexed and matched manner substantially around the surface of the main outer flange and inner flange lips or ledges, which extend beyond the periphery of the container.
When the welding ridges or strips are seated and driven against the surfaces of the channels, they effect an ultrasonic weld that is properly indexed as well as such where it drives against a surface for plastic flow of the materials.
An enhancement of this invention is the utilization of expanded portions in the welding channels with expansion gaps. These expanded portions or expansion gaps permit the weld to take place without undue displacement by either the heated materials or gases created during the welding process. The gaps, which can be in the form of offsets, depressions, or other expansion areas, allow for the expansion of gas or materials to provide, an effective weld taking place without being dislocated or driving the weldment into a displaced relationship.
It has been found with the expansion gaps or depressions, that a stronger weld takes place and a significant elimination of failures of the weld have been eliminated.
A further enhancement of this invention is the utilization of spacers or ribs between the inner shell and outer shell. The spacers or ribs allow for indexing of the inner and outer shell together for proper placement of the eutectic gel as well as orientation during the welding process. Further to this extent, they also enhance and rigidify the overall wall structure of the inner and outer shell to provide for a strengthened composite food container.
Another feature and objective of this invention is to allow for the stacking of the units both before and after welding of the inner and outer portions. The stacking of the units can be accomplished so that multiple inner or outer shells can be stacked together prior to the welding process. This allows for continuity of the process without the necessity of handling each inner or outer shell on a singular basis so that they can be handled fundamentally on a series basis.
Another feature of this invention is a ledge or step within the base portion of the completed product formed in the outer shell. This allows for the completed products to be stacked together both when in use and not in use. Thus, multiple units can be handled and placed within a preconditioning temperature environment in order to create a series of them that can then be nested and separated at a later point.
The improved process relies upon the proper measurement of eutectic gel and any displacement thereof by the inner shell when joined together with the outer shell having the eutectic gel therein. The displacement is accomplished through a certain level to allow for expansion and contraction of the eutectic gel during the various temperatures at which it is used.
As a consequence, this invention is a significant step as to both the end product and the process in manufacturing the product.